SPATIAL FREQUENCY TUNED COVARIANCE CHANNELS UNDERLYING SCOTOPIC CONTRAST SENSITIVITY

2000 ◽  
Author(s):  
DAVID H. PETERZELL ◽  
BROOKE E. SCHEFRIN ◽  
STEPHEN J. TREGEAR ◽  
JOHN S. WERNER
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity

scholarly journals Contrast sensitivity in 1/f noise considered across spatial frequency band

2010 ◽  
Vol 8 (6) ◽  
pp. 349-349
Author(s):  
A. M. Haun ◽  
E. A. Essock
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Frequency Band

No Sex Differences in Contrast Sensitivity and Reaction Time to Spatial Frequency

2002 ◽  
Vol 94 (3) ◽  
pp. 1053-1055 ◽  
Author(s):  
Jennifer L. Solberg ◽  
James M. Brown
Keyword(s):  
Sex Differences ◽  
Reaction Time ◽  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Frequency Information ◽  
Frequency Processing

This study investigated the possibility of sex differences in spatial frequency processing by measuring contrast sensitivity and reaction time to spatial frequency in the same 20 men and 20 women. This is the first study to investigate sex differences in reaction time to spatial frequency and the first to study sex differences in contrast sensitivity and reaction time within the same participants. No sex differences were found in either contrast sensitivity or reaction time measures, suggesting that women and men process spatial frequency information similarly.

scholarly journals Neuronal basis of perceptual learning in striate cortex

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Zhen Ren ◽  
Jiawei Zhou ◽  
Zhimo Yao ◽  
Zhengchun Wang ◽  
Nini Yuan ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Perceptual Learning ◽  
Contrast Sensitivity ◽  
Striate Cortex ◽  
Signal To Noise Ratio ◽  
High Spatial Frequency ◽  
Sensitivity Training ◽  
Spatial Frequencies ◽  
Cortex Area ◽  
Adult Cats

Abstract It is well known that, in humans, contrast sensitivity training at high spatial frequency (SF) not only leads to contrast sensitivity improvement, but also results in an improvement in visual acuity as assessed with gratings (direct effect) or letters (transfer effect). However, the underlying neural mechanisms of this high spatial frequency training improvement remain to be elucidated. In the present study, we examined four properties of neurons in primary visual cortex (area 17) of adult cats that exhibited significantly improved acuity after contrast sensitivity training with a high spatial frequency grating and those of untrained control cats. We found no difference in neuronal contrast sensitivity or tuning width (Width) between the trained and untrained cats. However, the trained cats showed a displacement of the cells’ optimal spatial frequency (OSF) to higher spatial frequencies as well as a larger neuronal signal-to-noise ratio (SNR). Furthermore, both the neuronal differences in OSF and SNR were significantly correlated with the improvement of acuity measured behaviorally. These results suggest that striate neurons might mediate the perceptual learning-induced improvement for high spatial frequency stimuli by an alteration in their spatial frequency representation and by an increased SNR.

Specific reading disability: differences in contrast sensitivity as a function of spatial frequency

Science ◽  
1980 ◽  
Vol 210 (4468) ◽  
pp. 439-440 ◽  
Author(s):  
W. Lovegrove ◽  
A Bowling ◽  
D Badcock ◽  
M Blackwood
Keyword(s):  
Spatial Frequency ◽  
Reading Disability ◽  
Contrast Sensitivity ◽  
Specific Reading Disability ◽  
Specific Reading

The effects of grating area and spatial frequency on contrast sensitivity as a function of light level

1993 ◽  
Vol 33 (15) ◽  
pp. 2065-2072 ◽  
Author(s):  
Juvi Mustonen ◽  
Jyrki Rovamo ◽  
Risto Näsänen
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Light Level

Spatial Integration of Objectively Equiluminous Chromatic Gratings

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 200-200
Author(s):  
M I Kankaanpää ◽  
J Rovamo ◽  
H T Kukkonen ◽  
J Hallikainen
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Spatial Integration ◽  
Chromatic Contrast ◽  
Shape Difference ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Chromatic Aberrations ◽  
Chromatic Contrast Sensitivity

Contrast sensitivity functions for achromatic and chromatic gratings tend to be band-pass and low-pass in shape, respectively. Our aim was to test whether spatial integration contributes to the shape difference found at low spatial frequencies. We measured binocular chromatic contrast sensitivity as a function of grating area for objectively equiluminous red - green and blue - yellow chromatic gratings. Chromatic contrast refers to the Michelson contrast of either of the two chromatic component gratings presented in counterphase against the combined background. Grating area ( A) varied from 1 to 256 square cycles ( Af2) at spatial frequencies ( f) of 0.125 – 4.0 cycles deg−1. We used only horizontal gratings at low and medium spatial frequencies to minimise the transverse and longitudinal chromatic aberrations due to ocular optics. At all spatial frequencies studied, chromatic contrast sensitivity increased with grating area. Ac was found to be constant at low spatial frequencies (0.125 – 0.5 cycles deg−1) but decreased in inverse proportion to increasing spatial frequency at 1 – 4 cycles deg−1. Thus, spatial integration depends similarly on spatial frequency for achromatic (Luntinen et al, 1995 Vision Research35 2339 – 2346) and chromatic gratings, and differences in spatial integration do not contribute to the shape difference of the respective contrast sensitivity functions.

scholarly journals Contrast sensitivity and behavioural evidence for lateral inhibition in octopus

2019 ◽  
Vol 15 (5) ◽  
pp. 20190134 ◽  
Author(s):  
Luis Nahmad-Rohen ◽  
Misha Vorobyev
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity ◽  
Lateral Inhibition ◽  
Neural Processing ◽  
Visual Systems ◽  
Maximum Value ◽  
Fixation Reflex ◽  
First Time ◽  
The Brain ◽  
Behavioural Evidence

Behavioural contrast sensitivity in Octopus tetricus was measured in the range of 0.05–12 cycles per degree (cpd) using a fixation reflex. We show that the contrast sensitivity reaches its maximum (between 1 and 4%) at 0.3 cpd, and decreases to approximately half of the maximum value at the lowest spatial frequency. Reduction of sensitivity at low spatial frequency is a signature of lateral inhibition in visual systems. In vertebrates and insects, lateral inhibition helps to overcome the bottleneck of encoding information into spikes. In octopus, photoreceptors generate spikes themselves and are directly connected to the brain through their axons. Therefore, the neural processing occurring in the octopus brain cannot help overcome the bottleneck of encoding information into spikes. We conclude that, in octopus, either the lateral inhibition occurs in the brain after information has been encoded into spikes, or photoreceptors inhibit each other. This is the first time behavioural contrast sensitivity has been measured in a cephalopod.

Modelling the dependence of contrast sensitivity on grating area and spatial frequency

1993 ◽  
Vol 33 (18) ◽  
pp. 2773-2788 ◽  
Author(s):  
Jyrki Rovamo ◽  
Olavi Luntinen ◽  
Risto Näsänen
Keyword(s):  
Spatial Frequency ◽  
Contrast Sensitivity
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